1. Field of the Invention
The present invention relates generally to a snow guard system capable of being attached to a roof, which is used to prevent snow from sliding off the roof, and more particularly to an improved clamping means for securing such snow guard systems to a roof seam.
2. Related Art
Sliding snow and/or ice from roofs can be hazardous to people, the surrounding landscape, property, and building components. The problem of sliding snow or ice is particularly prevalent in connection with raised seam metal roofs, where there is relatively little friction between the roof and the snow or ice.
As shown in FIG. 1, conventional snow guard systems 200 have long been used for controlling movement of snow and ice across selected areas of roofs by preventing sliding of snow and ice down the pitch of the roof. Recently, these snow guard systems have increased in popularity, and currently several snow guard mounting systems serve to hold snowloads on roofs. For example, one such snow guard system is discussed in Applicants pending application Ser. No. 09/280,635, entitled "SNOW GUARD SYSTEM HAVING A FLAG TYPE ATTACHMENT," which is incorporated herein by reference in its entirety.
Since the advent of snow guard systems, inventors have adopted a number of means for securing the snow guards to a roof. For example, see U.S. Pat. No. 3,880,405. With the advent of raised seam metal roofs, it has become particularly problematic to attach conventional snow guards thereto. A typical metal roof comprises a plurality of metal roofing panels that are laid side by side to cover the width of a roof section. Each panel usually includes substantially perpendicular edges running along both the left and right sides thereof. The roofing panels are located such that their substantially perpendicular edges arc abutting, thereby forming a seam therebetween. The substantially perpendicular edges of the abutting panels are each typically crimped together and/or bent downwardly over each other to form a joint. The joint seals the adjoining panels, thereby preventing fluid communication to the roofing substructure below the roofing panels, as well as to the area between each roofing panel. Various metal roof installers have devised unique patterns for the joints, and as a result a wide variety of joints exist.
As shown in FIG. 1B, in snow guard assemblies used on seamed metal roofs, the assembly is typically attached to the roof seam using a mounting block 18 secured by an attachment means. For instance, one possible attachment method is via screws or bolts. However, both screws and bolts require puncturing the roofing seam 12 to hold the assembly in place. Once the snow guard assembly is removed, any holes created by the screws or bolts remain, thereby destroying the hermeticity of the metal roof. Moreover, such holes allow water to contact the roof substructure even while the snowguard is still attached.
To solve this problem, the Applicant had previously developed an attachment device capable of being attached to a metal roof without tearing, puncturing or otherwise destroying the hermeticity of the metal roof seam 12. This attachment device is described in detail in Applicant's U.S. Pat. No. 5,613,328, the entirety of which is incorporated herein by reference.
According to the teachings of this patent, as shown in FIGS. 2A and 2B, a device was provided capable of being attached to a metal roof seam 12. This device includes a mounting block 18 having a first side wall 52 and a second side wall 54, a base 53 and a top 51. A groove 24 located in the base 53 of the block 18 allows the block 18 to be located on the metal roof by placement of the groove 24 about a segment of the seam 12. A first threaded hole 62 is located in the block between the first side wall 52 and the groove 24. In order to attach the mounting block 18 to the seam 12, a ball 100 and first set screw 102 is provided. The ball 100 has a substantially curved surface 101. A first set screw 102 is translocatable within the first threaded hole 62. This first set screw 102 has a first terminal end 104 juxtaposed with the ball 100 such that the curved surface 101 of the attached mechanism 100 and 102 is diametrical thereto and is pivotable thereabout. As shown in FIG. 2A, the first set screw 102 further has a second terminal end 106 drivable into the first threaded hole 62. As shown in FIG. 2B, driving the first set screw 102 into the first threaded hole 62 would cause the substantially curved surface 101 of the ball 100 to engage a first portion 105 of the seam 12 of the metal roof. Consequently, rotational movement of the curved surface 101 of the ball 100 is precluded relative to the first portion 105 of the seam 12 as the ball engages the seam 12. As a result, the first set screw 102 pivots about the curved surface 101 of the ball 100. Moreover, further driving of the first set screw 102 causes the first engaged portion 105 of the seam 12 to be driven towards the portion of groove 24 diametric thereto, thereby forming a pocket in the first engaged portion 105 of the seam 12. As a result, the mounting block 18 could be secured to the roof without piercing or tearing the seam 12.
Although this method of attachment represented a vast improvement over the prior attachment methods, there is still room for improvement.
For example, in the ball and screw arrangement, the entire holding force per attachment mechanism is limited to the force which can be applied through an individual contact surface. That is, the contact area between the seam 12 and each ball 100 is limited to only a singular, independent contact surface 101. Because such a design requires that the entire contact force be applied through a single contact surface 101 on each ball 100, the total amount of static holding force (which is equal to the summation of the holding forces of each individual contact surface), is determined by the number of balls engaging the roof seam 12. Since the holding force per attachment mechanism is limited to (the force transmitted through) the singular contact surface 101, the net holding force available for holding the mounting block in place is significantly limited.
Moreover, providing only a single contact surface results in a relatively unstable connection since sliding will occur if the force of the snow load exceeds the friction of force at that singular point of contact. Thus, if too few attachment mechanisms (i.e., ball 100 and set screw 102) are employed, the mounting block will be susceptible to separating from the seam under heavier snow loads and sliding along the seam when the force of the snowload exceeds the friction of force between the contact surface and the seam.
Thus, it would be desirable to apply a greater amount of pressure to the seam per attachment mechanism thereby eliminating the need to employ an excessive number of attachment mechanisms. It would also be desirable to distribute the contact load through a greater number of points over the length of the seam to prevent sliding. Accordingly, a need exists for an attachment mechanism that will decrease the amount of holding force applied through each contact surface, while maintaining enough pressure per attachment mechanism to hold the mounting block 18 in place when particularly heavy snowloads are applied.